>> A) What percentage of your CD's or music collection will you NOT
>> listen to again in the next 5 years but you hold onto them?

No idea... but I'd say that close to 0% that I can't imagine listening to. 
I like the experience of being able to always find something "new" (new to 
me that minute) in my own collection.  If there is something I don't care 
for, I ship it out or put it in my Lala bag for future trading.  But 
otherwise, if I've kept it, I probably can envisage listening to it again. 
I amass, but I don't horde (if that makes sense.)  Also, given how much 
music I have and how many listening hours there will be in the next 5 years, 
and factoring in new music listening time, I probably cannot physically 
listen to everything I have in 5 years.  But I do try to maintain my 
collection such that I might want to listen to everything.  Exceptions: 
stuff I keep because my wife likes it (we have morphed into a single 
collection, and I know I'M never playing that Lauryn Hill CD again); and 
live bootlegs that I've collected because they might "trade well" (stuff I 
think might have value to other traders.)

>> B) What percentage will you NEVER listen to again but you hold onto
>> them?

I think I've kind of answered this one above.

>> C) What does that mean to you if anything?

Nothing more than I've writ.  But one comment.  Stuart said he thins out 
based on, did he listen to something in the last 5 years.  That wouldn't 
work for me, because when I try something like that, I invariably pull out 
CDs and say, "Hey!  I haven't played this in over 5 years!" and then pop 
them in.